Description: (Applicant's Description) The goal of the Antigen and Antibody Production Shared Resource is to provide timely services to investigators that include: 1. GST-fusion protein production. 2. Mouse polyclonal antisera production. 3. Mouse monoclonal antibody. 4. Single cell cloning and cryopreservation of the subclone. 5. The use of above reagents in characterizing specific gene products. Genes important for cancer predisposition, progression, and prognosis are being identified at a remarkable pace. Accompanying these findings is the identification of their interacting proteins that are important for the gene function. Discoveries of BRCA1 and BRCA2, and subsequently, demonstration of their interaction with the DNA repair proteins, Rad51 and Rad50, have highlighted such discoveries in breast cancer studies. The timely development of purified fusion proteins facilitates studies of gene function and production of antibodies are required for the identification of specific gene products, immunostaining to localize the protein, screening gene mutation in cancer samples, and studies of interacting proteins. This core will provide a streamlined service once a cDNA fragment with open reading frame is obtained. Since GST-fusion proteins usually serve as excellent antigens, we will use purified GST-fusion proteins as antigens to produce polyclonal and monoclonal antibodies. High quality polyclonal antibodies, suitable for immunoprecipitation, immunoblotting and immunostaining, will be produced in mice house in the pathogen-free facility. A well-established hybridoma core facility will provide services on monoclonal antibody products. The core will also provide advice on approaches and services for protein product identification and localization of protein product, immunostaining, and image analysis of cell lines or tissue sections stained with a specific antibody. Since studies or protein products of newly identified tumor suppressor genes, signaling molecules, and their interacting molecules have important prognostic and diagnostic potential, providing well-characterized antibodies in a timely manner will meet the special needs of the SACI investigators.